EVALUATION OF PREEMERGENCE HERBICIDES FOR GOOSEGRASS (WIREGRASS, SILVER CRABGRASS) CONTROL ON A COMMON BERMUDAGRASS GOLF COURSE

Proposed by: Norman M.Nagata

Presenter: Nagata, N. M., Extension Agent (commercial Landscape, Turfgrass & Nurseries), Ctahr, University Of Hawaii At Manoa, Kahului, HI 96732

EVALUATION OF PREEMERGENCE HERBICIDES FOR GOOSEGRASS (WIREGRASS, SILVER CRABGRASS) CONTROL ON A COMMON BERMUDAGRASS GOLF COURSE

Nagata,* N. M.1

1. Extension Agent, Maui County Cooperative Extension Service, University of Hawaii at Manoa, College of Tropical Agriculture and Human Resources, Kahului, Hawaii 96732

Goosegrass, (Eleusine indica) is a difficult weed to control on golf courses in Hawaii. It grows perennially, produces many seeds, germinates readily and postemergence herbicides are relatively ineffective on older plants. In May 2009, a 3-month preemergence herbicide test was conducted on a common bermudagrass golf course rough with a heavy infestation of old goosegrass plants. The test consisted of 4’ x 4’ plots arranged in randomized complete blocks with 4 replicates. Goosegrasses were hand weeded then sprayed at 40 gal/acre with a mixture of a preemergence plus the postemergence herbicide Revolver (1.6 pt/a) and Spreader 90 (0.5 pt/100 gal). A granular preemergence was applied with a shaker bottle immediately after spraying with Revolver and Spreader 90. A week later, the postemergence Trimec Plus (1.6 gal/a) and Spreader 90 were sprayed over the plots. Both postemergences were applied to ensure the data was based solely on newly established goosegrass plants. Twelve weeks after treatment (WAT), the preemergence herbicide combination of Pendulum AquaCap (P-AC) (3.2 pt/a)/Tower (1.3 pt/a) was most effective by providing 94.9% control, followed by P-AC (3.2 pt/a)/Tower (2 pt/a) with 93.8% control, Ronstar (6 lb/a, 92.3% control), Barricade (2.3 lb/a, 91.3%), Freehand (200 lb/a, 86.8%), P-AC (3.2 pt/a, 72.2%), Tower (2 pt/a, 57.5%) and lastly by Tower at 1.3 pt/a with 35.0% control. Field days held at 6 and 13 WAT were attended by 47 stakeholders with 35 people partially responding to an evaluation. Thirty-two people said their knowledge had increased by 58.7%. Thirteen individuals will use the information within a month, 6 people within 6 months and 5 plan to use it in the future. The project received an 8.9 rating on its relevancy to their work (1 = not relevant, 10 = extremely relevant). Everyone said the information was useful and to continue these research projects. Attendees were able to obtain recertification credits from the Golf Course Superintendents Association of America and pesticide credits from the Hawaii Department of Agriculture.

All Accepted Proposals